Sunlight is the best medicine. Not a metaphor—science

How sunshine can shorten hospital stays and promote better healing

Supreme Court Justice Louis Brandeis famously remarked, “Sunlight is said to be the best of disinfectants.” While sunshine is known to kill bacteria, it can also cure people. During the tuberculosis pandemic, visionary architects designed hospitals that enabled maximum exposure to sunlight for recovering patients—and they recovered faster than patients not exposed to sunlight. Today, strategic use of sunlight has been shown to promote faster recovery from depression.

Pioneering nurse Florence Nightingale was rigorous not only about kindness and cleanliness—she maintained meticulous statistical records about her patients, to determine the most effective treatment practices.
In addition to encouraging good ventilation, promoting adequate sleep, providing a nutritious diet, and allowing plants and flowers in the sickroom (she knew that they provide oxygen and consume carbon dioxide, as well as provide a pleasant focus), Nightingale was an enthusiastic proponent of allowing as much natural light into the patient’s room as possible.

As she said in Notes on Nursing, “It is the unqualified result of all my experience with the sick, that second only to their need of fresh air is their need of light…. And that it is not only light but direct sun-light they want.” She knew that her patients in rooms facing east recovered more quickly than those in rooms facing other directions—or in windowless rooms. She observed her patients turning their faces toward light and compared them to plants following the sun in its course across the sky.

Similarly, before the development of antibiotic therapy for tuberculosis, sanatoriums addressed the worldwide pandemic with sunlight. Doctors noted that patients who lay in the morning sun gained more weight and went home sooner. This became standard practice around the world:

In 1903 Swiss doctor Auguste Rollier opened his “sunlight clinic,” which featured an enormous solarium on the roof and developed a slow, careful tanning process for new or especially feeble patients.

Deep in a Finnish forest, in 1929 architect Alvar Aalto built a sanatorium that prioritized access to natural light, enabling patients to benefit from the sun while resting comfortably in their rooms.

And in the early years of the 20th century, my grandmother’s parents ran a tuberculosis sanatorium in the beautiful small town of Otwock, Poland. The air was clear, the climate was sunny, and the patients—when they weren’t eating one of their eight daily meals—spent their time lying quietly in the sun, well bundled up in autumn and winter.

What Nightingale observed more than a century ago, modern science has now proven. Sunlight can reset a person’s circadian rhythms, enabling a healthier sleep-wake cycle and better healing. And it can be deployed strategically to treat mood disorders in particular. Don’t take my word for it—here’s some more recent evidence:

Pioneering chronotherapist Francesco Benedetti and his colleagues found that patients suffering from bipolar depression who were placed in rooms with an eastern exposure recovered almost four days faster than patients whose rooms had a western exposure. Similarly, another study found that patients admitted to two hospitals for depression—one with sunny rooms, one with darker rooms—stayed approximately three days less if they were in the sunnier rooms.

Benedetti also demonstrated that sunshine can be an effective, non-invasive, and safer intervention for bipolar depression, which can be tricky to treat as antidepressants frequently trigger a manic or mixed episode of the disorder. If administered soon after the onset of the depressive episode, sunshine can quickly alleviate depression without the risk of a subsequent mania.

A 2013 study of patients with cystic fibrosis and comorbid depression suggested that exposure to light significantly improved patients’ chance of depression remission.

A review of hospital admissions in Egypt, a country with year-round sunshine and a fairly stable climate, showed more admissions for depression in December, and more admissions for mania in June. In contrast, schizophrenia admissions did not vary by season. This is consistent with a large body of research that suggests that bipolar disorder is a circadian rhythm disorder.

A modern heir to Rollier and Aalto is Dr. Richard Hobday, who is what the British call a “chartered engineer.” I might not recognize that term, but I’m impressed by his research and practice. Dr. Hobday’s book “The Light Revolution: Health, Architecture and the Sun” delves into the history of how sunlight has been used to alleviate conditions ranging from rickets to heart disease. He advocates “Five Points of Solar Architecture for Health”:

Orient the building for sanitation and sunbathing;

Position the rooms for sunlight therapy and disinfection;

Put windows in more than one wall to let the sun in at different times of the day or year;

Ventilate naturally; and

Underfloor heating.

As I prepare for a (non-SAD related) surgery later this spring, I’m definitely going to ask the hospital if I can be placed into a room with an eastern exposure. And after I go home, I’ll be sure to spend plenty of my recovery time relaxing (well-sunscreened) in Central Park, soaking up the healing sunlight.

Abigail enjoys some healing sunshine

Abigail Strubel, MA, LCSW, CASACAbigail is a Columbia-educated clinical social worker and certified alcohol and substance abuse counselor. She uses light therapy to cope with her annual seasonal affective disorder, and also manages chronic insomnia through acupressure and good sleep hygiene. She has worked with formerly homeless adults, ex-offenders on parole, recovering heroin users, and other interesting populations. Abigail’s posts at the Center for Environmental Therapeutics fuse humor with practical insights about mood, sleep, and alertness–a combination we wanted to share with the world beyond cet.org. She advocates a holistic approach to health and wellness.

CET is an independent, non-profit professional organization dedicated to education and research on the new environmental therapies. We offer a variety of services, including background information, self-assessment questionnaires, and environmental therapy products.

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